TiO2 is an efficient photocatalyst at ultraviolet and near visible light wavelengths for use in hydrogen production, self-cleaning, and decomposing volatile organic compounds. However, TiO2 by itself can only reach a certain level of photocatalytic efficiency due to the quick recombination of the photo-generated electron-hole pairs. To further improve the photocatalytic performance, combining TiO2 with another semiconductor with a similar position in their conduction bands or metal nanoparticles, can produce a so-called charge separation effect to extend the lifetime of the electron-hole pairs. Typically metals such as Ag, Au, and Pt have been used to scavenge photo-generated electrons and have shown significant charge-separation enhancement. However, the most common method to prepare these structures is to coat the TiO2 layer with a metal on top. The metal nanoparticles cover the surface of the TiO2, and thus reduce the surface area between TiO2 and the liquid, which then reduces the area of the catalytically active sites. When combining TiO2 with a semiconductor, the second material can be placed under the TiO2, and thus can have the benefit of allowing all of the TiO2 to be in contact with the liquid while its photocatalytic properties are being enhanced by the other semiconductor.